module.parent is incorrectly circular in ^22.

[jdalton]

Hi!

I'm seeing mocked module.parent be a circular reference in test files

// in my test file
module.parent === module // true, but not supposed to be

[SimenB]

From #4614, I guess. Would you expect module.parent to be null in the test file?

PR: #5241

[jdalton]

The module.parent is the first module to require it. So I'd guess some jest file.

[stieg]

As an FYI to add to the severity of this issue this problem causes the require_optional package to get stuck in an infinite loop; which can cause people who are trying to use mongoose 5 with jest to have hanging tests. There is a PR out to fix the issue but it has not been merged as of yet.

In regards to what is expected in Jasmine the parent module of the test module is a Jasmine module. And eventually the module parent leads to a falsy. Here is the test I wrote to confirm this in Jasmine (this fails in Jest):

it('Test module parent does end', () => {
  let i = 100;
  let mod = module;
  while (i-- > 0 && mod) {
    mod = mod.parent;
  }
  expect(mod).toBeFalsy();
  expect(i).toBeTruthy();
});